1. Field of the Invention
The present invention relates to a silicone resin composition, which is curable at a temperature of not more than 270.degree. C., particularly in a range of 150.degree. to 270.degree. C., for forming a thin film of a silicone ladder polymer.
2. Background of the Invention
A silicone ladder polymer, which is a ladder type silicone resin material, is well known as a heat resisting polymer. Such silicone ladder polymer has excellent heat resistance, water resistance and electrical insulability. In consideration of such properties, study has been made as to application of this polymer to a protective coat, an interlayer isolation film etc. for an electronic component or a semiconductor device.
In such application to an isolation film or the like, it is necessary to cure the silicone ladder polymer by heat treatment, in order to attain solvent resistance. According to Japanese Patent Laying-Open No. 55-94955 (1980), such heat treatment must be performed under a high temperature of at least 350.degree. C. so that the silicone ladder polymer is not dissolved in a good solvent. Due to requirement for such high-temperature heat treatment, however, application of the polymer is restricted. In other words, it is impossible to form a thin film of this polymer, which has excellent solvent resistance, on a substrate or device which is inferior in heat resistance.